548 ALIAS: Vor, X11 
the top of the coronoid process of the mandible, the planes 
extending obliquely into the muscle from its outer surface, but 
not passing entirely through it excepting at or near its inser- 
tion. The separation, therefore, on the external surface of the 
muscle extends much nearer its origin than in its deeper por- 
tions. The plane between the upper and middle portions of 
the muscle extends downward, backward, and inward; that 
between the middle and lower portion almost directly down- 
ward and inward; so that the line separating these two parts 
on the outer surface of the muscle runs almost directly back- 
ward from the tip of the coronoid process. The lower or pos- 
terior division of the muscle overlaps the middle one and so lies 
partly superficial to it, and the middle portion in the same way, 
but to a much greater extent, overlaps and lies superficial to the 
upper or anterior one. The separation between the lower and 
middle divisions is much more complete than that between the 
middle and upper ones. 
The outer and upper fibres of the lower portion, A2’, have 
their insertion on the outer surface of the supra-angular, near 
its hind edge, and on that hind edge from the tip of the coro- 
noid process to the lower end of the bone. At the top of the 
coronoid process they extend almost onto a strong tendon or 
ligament (No. 76, p. 126), which has its origin there and is 
inserted on the inner surface of the maxilla at about its ante- 
rior third. The connective tissue sheath covering this portion 
of the muscle at its insertion is continuous with that covering 
the ligament, so that, before it is removed, the ligament has 
strongly the appearance of being the tendon of the muscle. 
The remaining deeper and lower fibres of Az’ separate from the 
outer ones and are inserted on the inner surfaces of the artic- 
ular, the supra-angular, and the coronary cartilage. This por- 
tion of the muscle is continuous at its lower, ventral margin, and 
toward its origin, with the lower fibres of 3, the two muscles 
sometimes enclosing between them, intimately connected with 
them, a special bundle of fibres (Fig. 37, Pl. X XIX), which arise, 
partly tendinous, from among their fibres, and, joining the man- 
dibular portion of the adductor, Ao, at its hind edge, are in- 
serted continuous with that muscle on the inner surface of the 
